(1) Field of the Invention
The present invention relates to a novel bis-urea compound, a process for producing the compounds and a novel process for producing an aprotic polar compound 1,3-dialkyl-2-imidazolidinone represented by the formula (2): ##STR1## wherein R is an alkyl group, by using the bis-urea compounds.
The compounds represented by the formula (2) are a useful substance as an aprotic polar solvent and an intermediate for medicines and agricultural chemicals. The compounds are particularly excellent solvent for high polymers such as polyamides, polyvinyl chloride, polyvinyl alcohol, polystyrene, polyurethane and phenolic resins. Further, the compounds dissolve many inorganic compounds with ease and can be used as a solvent for various characteristic organic reactions.
(2) Prior Art of the Invention
Various processes have been proposed on the preparation of 1,3-dialkyl-2-imidazolidinones represented by the formula (2): ##STR2## wherein R is an alkyl group. For example, on 1,3-dimethyl-2-imidazolidinone, a process wherein ethylenediamine is reacted with urea to obtain 2-imidazolidinone which is subjected to addition reaction to formaldehyde, followed by reducing the resulting reaction product with trichloroacetic acid, formic acid or the like, into the corresponding N,N'-dimethylated compound; a process having improved the above reducing process wherein hydrogenation decomposition is carried out using a noble metal catalyst in an acidic state; a process wherein N,N'-dialkylethylenediamine is reacted with phosgene or trichloroformate while it is decomposed into phosgene, etc. have been known.
The present inventors previously proposed a commercial process for producing 1,3-dialkyl-2-imidazolidinones in good yield by reaction of N,N'-dialkylethylenediamines with urea (U.S. Pat. No. 4,731,453). However, preparation of the raw material N,N'-dialkylethylenediamines from dichloroethane and alkylamines leads to formation of a by-product N,N',N"-trialkyldiethylenetriamines. Consequently, the yield of 1,3-dialkyl-2-imidazolidinones on the basis of dichloroethane is unsatisfactory in industry. For example, the yield is 68% in 1,3-dimethyl-2-imidazolidinone, 70% in 1,3-diethyl-2-imidazolidinone, 82% in 1,3-dipropyl-2-imidazolidinone and 85% in 1,3-dibutyl-2-imidazolidinone. Further, application of the by-product N,N',N"-trialkyldiethylenetriamines in a large amount has not yet been found and development of uses has been strongly desired.